Access Google IAP protected API from Angular - google-app-engine

My application has 2 modules
Spring boot back-end API
Angular front-end (SPA application)
Both were deployed in Google app engine (GAE).
I used Google IAP for authentication. After enabling the IAP is there any way to generate the IAP JWT token for the different users within the organization to authenticate the APIs from the web client.
I tried token generating mechanism using the Service account. But for my scenario, I just want to authenticate and authorize users not service account. I found this reference to enable the web resource access for users, but it is using cookie based authorization. And it is not the recommended way for the application such as angular.

If you're using IAP to protect your backend api, it means your users have a Google Account or an account managed in Cloud Identity.
In your Angular front-end app, you can retrieve JWT token of your user, with Google Sign-In for Websites.
To easily integrate Google Sign-in with Angular, I recommend you to use ng-gapi from Ruben.
Main lines of the workflow :
Angular uses ng-gapi with Google Sign-in behind the scene
Users are authenticated with their Google Account
You're able to retrieve GoogleUser idToken which is a JWT token.
Each HttpRequest could be executed with Authorization: Bearer JWT
IAP will accept request.
To better understand how to use ng-gapi, check this stackblitz Demo made by creator of lib.
I also suggest you theses resources :
My answer on Stackoverflow about Angular stateless authentication workflow. Just skip the Spring Boot JWT part if you're using IAP.
Google Sign-In for Websites official docs.
Note that you need to use the OAuth 2.0 Client ID configured by Identity-Aware Proxy for your app, and add the correct Authorized JavaScript origins.

Yes, You can generate a JWT token using angular-oauth2-oidc.
Get the default IAP Web App client ID and client secret. Use AuthConfig and redirect to your link after credentials are entered; you can capture the token after they are redirected.
This link has all the details:
https://medium.com/#ishmeetsingh/google-auth-integration-with-angular-5-and-angular-oauth2-oidc-ed01b997e1df
You have told that you tried authenticating from service account. Were you able to generate JWT for service account? I am able to capture the JWT token for individual accounts and use it.
Please give more information on how you authenticated from service account.
Thanks,
Bharath

Related

Oauth for authorization JWT for authentication for an app using DRF and cloud functions

I'm building a web app with Wagtail as back-end, running on app engine, cloud functions doing micro-services and triggered via http.
I want to let my users register and authorize using social apps and classic login-password and get a JWT token from Wagtail App. Then, the token will be used to authenticate users both on cloud functions and Wagtail back-end.
How do I provide the user with JWT tokens if he/she authorizes with OAuth?
Is my approach correct? Any suggestions on how this should be done in the proper way?
The best solution I found so far is to use firebase auth. In python I verify token like that:
from firebase_admin import auth
decoded_token = auth.verify_id_token(id_token)
uid = decoded_token['uid']

Google App Engine service-to-service authentication (non-programmatic)

I have a scenario where I have an on-premise GUI application which has a "Web Service Invoke" component which I use to call a GAE API.
In the GUI application, it is possible to:
store credentials
create a chain of web services/http(s) calls that can integrate an output of preceding https(s) call as a query parameter or header value into the next http(s) call
retrieve a value from JSON response of the http(s) call
But it is not possible to programmatically do anything. The Web Service widget has fields for passing API URL, query parameters and headers only.
I'm looking to do a service-to-service authentication for the API call and the API should be protected using IAP as well.
I'm aware of the recommended approach is to create a service account and provide the service account JSON key file to the client and the client signs a JWT token and pass it as a bearer token. But as I only have widgets, no programming possible, therefore signing JWT token is not an option.
I was looking at Google OAuth or IAM APIs which can support "client_credentials" grant type wherein I can get an access token using just clientId and clientSecret - something possible in Apigee. But it seems this grant type is not supported by Google OAuth APIs.
I also looked at Cloud Endpoints using API KEY - so the current thought is to the client passes API KEY in header/parameter for authentication to Cloud Endpoints, then Cloud Endpoints uses its service account to get access through IAP, and finally, I'm thinking that the client can also send in "Basic Auth" credentials through Authorization header which the GAE API backend service validates. The additional "Basic Auth" is because Google recommends using another auth method in addition to API KEY.
I would like a simpler solution if possible using GAE and IAP only. Any other suggestions, especially using time-limited tokens, that can work over only http(s) calls (non-programmatic or client library), is much appreciated.
Any alternatives or things to try is also appreciated.
Look into this server-to-server authentication using JWT Google API Authentication

How to use google authentication for an angular web app and a .net web api hosted on azure

I have an angular web app talking to a c# .net web api back end.
They are both hosted on azure app services.
Azure app services offers a suite of authentication services and I've chosen to use google auth.
I've got my google client id and secret setup in azure google auth and my web app correctly shows and prompts me for my google credentials.
My problem now, is that i need my web api back end to authenticate the web app google token. I couldn't find any articles or tutorials that demonstrates the following:
How to get and send the token to the web api? I've read that azure app service should automatically inject the necessary auth headers but any calls to my api do not include those headers. Should i manually call auth/me and add them to the request header?
How do i get my web api to authenticate the details from the request header with google auth? Do i need a separate client id for the web api or should i re-use the web app client id?
Cheers!
According to your description, I assumed that you are using the built-in Authentication / Authorization provided by Azure App Service.
AFAIK, App Service Authentication (Easy Auth) provides two flows: client-managed and server-managed flow. For the server-managed flow, the server code manages the sign-in process for you, and your backend would directly receive the token from the relevant identity provider (e.g. Google, AAD,etc.), then both generate a authenticationToken for browser-less apps and AppServiceAuthSession cookie for browser apps. Details you could follow Authentication flow.
For your angular web app, you could just use server-managed flow, after user successfully logged, you need to call https://<your-angular-app-name>.azurewebsites.net/.auth/me to retrieve the google access_token, then send the following request against your web api endpoint for retrieving the authenticationToken as follows:
POST https://<your-webapi-app-name>.azurewebsites.net/.auth/login/google
Body {"access_token":"<the-google-access-token>"}
After successfully retrieved the authenticationToken from your Web API endpoint, you could send the following subsequent requests for accessing your APIs:
GET https://<your-webapi-app-name>.azurewebsites.net/api/values
Header x-zumo-auth:"<authenticationToken-generated-by-your-webapi>"
Moreover, you could also use client-managed flow in your angular web app, you may need to directly contact with your identity provider (Google) to retrieve the access_token in your client via Auth0 or google-signin or other third-party libraries. Then you may need to both send request to your angular web app and Web API web app for retrieving the authenticationToken as the above request sample.
Do i need a separate client id for the web api or should i re-use the web app client id?
Per my understanding, you must use the same google application. For AAD authentication, you could configure a AAD app with the access permissions to another AAD app.

How can multiple services re-use the authentication cookie?

I want to understand how a static site with no backend can use okta with other custom API services hosted on other platforms.
Scenerio:
Website is a angluar/reactjs that is hosted as a "static" website.
I'm assuming when you authenticate using okta in e.g. react/angular website I am able to store the okta session id in local storage or cookie.
How say I create a web service and host that on heroku, how can I figure out if the user has authenticated or not and re-use the session?
The scenario where you have:
A JavaScript frontend application, hosted statically
A backend web service (API), that the JavaScript app makes API requests to
is a classic single-page app (SPA) scenario. The recommended authentication flow is the OpenID Connect implicit flow.
In plain English, you are:
Setting up your JavaScript app to talk to Okta (or another OpenID Connect identity provider)
Getting an access token from the identity provider
Attaching the access token to an API request to authorize it
Your API service could be running on Heroku, or somewhere else. In your API service code, you have to validate the access token before you decide to accept the request. The API service can go back and talk to the identity provider to determine if the user's access token is still valid.
How the API service validates the token depends on what language you are using to build your API service. But, that's basic idea: the access token is what authorizes the user's requests.

Server-side OAuth for user impersonation via GMail API

I am trying to perform server-side OAuth so I can use a specific user account in my domain to send emails (hence using GMail API) via my application.
Mine is a purely server-side app and I cannot perform "user consent" via a UI.
I have created a project in Google App Engine and have obtained service account credentials (P12 key).
My code looks like this -
new GoogleCredential.Builder()
.setTransport(httpTransport)
.setJsonFactory(JSON_FACTORY)
.setServiceAccountId(googleEmailerServiceAccountId)
.setServiceAccountPrivateKeyFromP12File(new File(googleEmailerServiceAccountPrivateKeyLocation)).setServiceAccountScopes(Collections.singleton(GmailScopes.GMAIL_COMPOSE))
.setServiceAccountUser("xxx#xxx.com")
.build()
I have delegated domain wide access to the application (for GMAIL COMPOSE scope) via the admin console as per https://developers.google.com/identity/protocols/OAuth2ServiceAccount.
And I still get an Unauthorised 401 when I try to send emails from my app.
Since there is no explicit documentation for the Gmail API that says it allows domain wide delegation, I am guessing it is not allowed for Gmail.
Is there any way of achieving this programatically?
Any idea would be much appreciated.
Thanks!
As far as I know you cant use a service account with Gmail. Service accounts must be pre authorized.
Authorizing Your App with Gmail
All requests to the Gmail API must be authorized by an authenticated
user. Gmail uses the OAuth 2.0 protocol for authenticating a Google
account and authorizing access to user data. You can also use Google+
Sign-in to provide a "sign-in with Google" authentication method for
your app.
Share a Google drive folder with the Service account. Add the service account email as a user on a google drive folder it has access
Share a Google calendar with the service account, just like any other user.
Service accounts don't work on all Google APIs. To my knowledge you cant give another user access to your Gmail so there will be now to pre authorize the service account.
Recommendation / work around / hack
Create a dummy app using the same client id, authenticate it get the refresh token then use the refresh token in your application.

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